西太湖秋季蓝藻水华过后细胞裂解对溶解性有机碳影响

从2009年7月~2010年3月每月采集西太湖表层水样,分析叶绿素含量﹑蓝藻细胞裂解速率﹑磷酸盐浓度的变化,并通过切向流超滤系统分离得到的高分子量(1kDa~0.5μm)溶解性有机物的碳氮比值和高分子量溶解性有机碳浓度的变化.结果表明,西太湖蓝藻细胞裂解速率在11月达到最大值(0.43d-1),而磷酸盐和高分子量溶解性有机碳浓度分别在12月与9月达到最大值.细胞裂解速率与磷酸盐﹑高分子量溶解性有机碳浓度之间没有相关性,说明水华过后影响磷酸盐浓度﹑高分子量溶解性有机碳的因素很多,蓝藻细胞裂解只是其中重要因素之一.藻类水华的出现可能导致水体中其它磷形态(如有机磷)与磷酸盐之间的迁移转化,而大型浅水湖泊扰动导致的沉积物再悬浮和水华过后频繁的细菌活动都可能是影响高分子量溶解性有机碳的因素.秋季水华过后蓝藻细胞裂解释放的有机碳进入微食物网循环,引起细菌活动频繁,而溶解性有机物中含碳化合物比含氮化合物容易降解,所以碳氮比值逐渐减少.此外细菌通过硝酸盐合成溶解性有机氮也可能是碳氮比值减少的一个重要原因.     

When does centrality matter? Scientific productivity and the moderating role of research specialization and cross‐community ties

The present study addresses the ongoing debate concerning academic scientific productivity. Specifically, given the increasing number of collaborations in academia and the crucial role networks play in knowledge creation, we investigate the extent to which building social capital within the academic community represents a valuable resource for a scientist's knowledge‐creation process. We measure the social capital in terms of structural position within the academic collaborative network. Furthermore, we analyse the extent to which an academic scientist's research specialization and ties that cross‐community boundaries act as moderators of the aforementioned relationship. Empirical results derived from an analysis of an Italian academic community from 2001 to 2008 suggest academic scientists that build social capital by occupying central positions in the community outperform their more isolated colleagues. However, scientific productivity declines beyond a certain threshold value of centrality, hence revealing the existence of an inverted U‐shaped relationship. This relationship is negatively moderated by the extent to which an academic focuses research activities in few scientific knowledge domains, whereas it is positively moderated by the number of cross‐community ties established. Copyright © 2012 John Wiley & Sons, Ltd.     

清远市乐排河氰化物跨境污染应急处理案例分析

近年来突发性跨境污染事件时有发生,广州市环保局曾先后成功处理北江镉污染、清远市乐排河氰化物污染等事件。本案例通过回放对清远市乐排河氰化物污染事件的应急处理过程,总结出环保部门应对突发性跨境污染事件三方面的思考：1.加强对跨境河流的监控是及时掌握突发性污染的必要手段;2.借鉴同类型污染事件的处理方法是有效处理事件的捷径;3.环保部门严格按职责处理是解决跨境污染事件的关键。     

酸化油水解废水脱酸处理工艺研究

酸化油是生产生物柴油的原料,其生产过程中产生的水解废水有机物含量高且具有强酸性,直接排放会严重污染环境。因此,对酸化油水解废水处理工艺进行研究有重要意义。通过对酸化油水解废水脱酸处理的条件及影响因素进行研究,并通过L9(34)正交实验确定了脱酸的最佳工艺条件。pH值为10,搅拌时间为15 min,温度为30℃是脱酸处理的最佳条件。     

新式十字轴径向挤压模具

此文提出了一种新式的十字轴径向挤压模具,此模具动作平稳可靠,生产率高,模具寿命较长,稍加改进后,此模具可适用于各种枝状件径向冷挤压或热锻.     

Statistics: an essential technology in environmental research and management

Statistical methods as developed and used in decision making and scientific research are of recent origin. The logical foundations of statistics are still under discussion and some care is needed in applying the existing methodology and interpreting results. Some pitfalls in statistical data analysis are discussed and the importance of cross examination of data (or exploratory data analysis) before using specific statistical techniques are emphasized. Comments are made on the treatment of outliers, choice of stochastic models, use of multivariate techniques and the choice of software (expert systems) in statistical analysis. The need for developing new methodology with particular relevance to environmental research and policy is stressed.Dr Rao is Eberly Professor of Statistics and Director of the Penn State Center for Multivariate Analysis. He has received PhD and ScD degrees from Cambridge University, and has been awarded numerous honorary doctorates from universities around the world. He is a Fellow of Royal Society, UK; Fellow of Indian National Science Academy; Foreign Honorary Member of American Academy of Arts and Science; Life Fellow of King's College, Cambridge; and Founder Fellow of the Third World Academy of Sciences. He is Honorary Fellow and President of International Statistical Institute, Biometric Society and elected Fellow of the Institute of Mathematical Statistics. He has made outstanding contributions to virtually all important topics of theoretical and applied statistics, and many results bear his name. He has been Editor of Sankhya and theJournal of Multivariate Analysis, and serves on international advisory boards of several professional journals, includingEnvironmetrics and theJournal of Environmental Statistics. This paper is based on the keynote address to the Seventh Annual Conference on Statistics of the United States Environmental Protection Agency.     

考虑等待位置的航空器交叉滑行冲突概率模型

为解决交叉道口冲突范围定义不完整等问题,提出了航空器交叉滑行冲突概率模型。该模型针对交叉滑行道结构特点,以T型交叉口为例,综合等待位置、机身长度、喷流范围等要素,扩展冲突区域,基于实时速度、位置变化构造冲突概率模型,并利用速度分布密度函数对模型求解。仿真验证表明:模型能计算不同运动状态的中型机在T型交叉口处的冲突概率,T型道口等待位置对冲突概率影响较大,等待位置较近将造成冲突判断延迟,等待位置较远会产生虚警误判,致使滑行中断。利用实际滑行轨迹验证,结果表明:模型能够再现T型道口上2架中型机滑行冲突产生、发展及解脱过程,计算结果与实际运行情况一致,能为管制员、飞行员提前判断冲突,及时采取措施提供依据。     

造纸黑液制备球形阳离子木质素吸附树脂

以造纸黑液中的碱木质素为原料,采用两步法制备球形阳离子木质素吸附树脂,并用扫描电镜和傅立叶变换红外光谱仪对其进行表征.第1步以造纸黑液中的碱木质素为原料,利用反相悬浮法制备球形木质素珠体,通过正交实验得出以占木质素质量1.5%的环氧氯丙烷为交联剂,吐温80为分散剂(含量为木质素质量的3%),煤油为分散相,O/W相比为3∶1,反应温度为90℃,搅拌速度为200r/min,反应时间1h为球形木质素珠体制备的最佳条件.第2步利用丙烯酰胺对球形木质素珠体接枝,得出以H₂O₂/Fe²⁺为引发剂,丙烯酰胺浓度为0.72mol/L,室温反应2h为接枝的适宜条件,在此条件下可得到离子交换容量为1.6405mmol/g的阳离子木质素吸附树脂.     

考虑驾驶方式的车辆与航空器交叉冲突评估*

为量化不同驾驶方式下车辆与航空器行驶风险,提出车辆与航空器交叉运行冲突评估模型,该模型将特种车辆驾驶方式分为激进、稳定、保守3类,综合驾驶特性和管制规则定义车辆速度演化规律,结合运行场景、间隔配备等要素确定冲突条件,并基于航空器与车辆实时速度、位置变化构造冲突评估模型。研究结果表明:冲突评估模型能够计算车辆与航空器在十型交叉口的冲突概率;激进方式下车辆先于航空器通过交叉口,风险概率均值相对最大,为0.679;保守方式下航空器先于车辆通过交叉口,最大间隔是安全间隔的4.7倍;稳定驾驶方式可兼顾安全和效率。本文模型能再现十型道口车辆与航空器交叉运行冲突产生、发展及解脱过程,计算结果可用于场面实时冲突识别和预警,能够为机场危险源识别和风险管控提供依据。     

高层建筑电气火灾隐患因子定量分析方法研究

为了对高层建筑电气火灾隐患排查进行定量化分析,采用解释结构模型构建高层建筑电气火灾隐患因子的复杂逻辑模型;在利用德尔菲法确定隐患因子初始概率的基础上,经过交叉影响分析法求解交叉影响概率矩阵;引入马尔科夫链修正各隐患因子交叉影响后的概率,得到火灾隐患因子的稳态概率矩阵。研究结果表明:各隐患因子的马尔科夫链校正概率比德尔菲法测定的初始概率更加准确,该计算排序结果可明确高层电气火灾隐患排查和管控的重点。